Presentation
Intermittent left flank pain
Patient Data
Ovoid hyperdense calculus in the left vesicoureteric junction with upstream left hydroureteronephrosis, renal AP pelvis diameter 19 mm.
Case Discussion
Uncontrasted computed tomography (CT) is the investigation of choice given its high sensitivity (>95%) and specificity (>96%) for the diagnosis of urinary tract calculi 1. In addition to being readily available and having short scan times, CT has the ability to demonstrate alternate causes of flank pain in 10-14% of patients suspected of renal calculi. Direct visualization of a calculus in the lumen of the ureter with upstream ureteric dilatation is a common finding 2.
Although not performed in this case, prone CT studies are often preferred since they allow distinction between a calculus retained in the intravesical segment of the distal ureter and one that is already passed into the bladder.